For manufacturing and conditioning cigarettes in packets, a type of conditioning machine is known which comprises a hopper having an inlet and a number of outlets, each of which outlets comprises closely-spaced partitions defining channels permitting the passage of one cigarette at a time. Each outlet also has a supporting surface located beneath the bottom ends of the channels and for supporting a layer of cigarettes arranged in an orderly succession and containing a given number of cigarettes.
The cigarettes are normally fed to the inlet in masses in which the cigarettes are substantially equioriented, i.e. oriented parallel to a given direction, and, in the case of filter-tipped cigarettes, with the filters located on the same side. Not infrequently, however, the masses also contain cigarettes oriented differently from the others, on account of the way in which the masses are transferred: either directly on conveyor belts or in boxes on box conveyors which empty the boxes into the hopper inlet. When conveying the cigarettes or emptying the boxes, in fact, it is virtually impossible to prevent some of the cigarettes from working into a position crosswise to said given direction. Such cigarettes are commonly referred to as "askewed" and create serious difficulties inside the hopper by blocking the outlet channels and forming so-called bridges, i.e. supporting structures defined by cigarettes. "Askewed" cigarettes therefore prevent through-flow of the cigarettes inside the hopper and result in stoppage of the entire conditioning machine.
EP-A1-545724 discloses a cigarette hopper having an inlet, a number of outlets, each of which comprises closely-spaced partitions defining channels allowing the passage of one cigarette at a time, and a chamber extending between the inlet and the outlets. The hopper disclosed in EP-A1-545724 also comprises a selecting apparatus, which is arranged inside the chamber and is designed to prevent vane jams of the cigarettes by means of a plurality of curved guides extending from the back to the front of the chamber.
The selecting apparatus disclosed in EP-A1-545724 partially eliminates the cigarettes jamming problems originated by the "askewed" cigarettes; however, this selecting apparatus does not work in an optimal manner owing to the difficulty of repositioning or eliminating the "askewed" cigarettes due to the forces, which act on the "askewed" cigarettes in the middle of the chamber and are due to the weight of the mass of cigarettes arranged in the upper portion of the chamber.